1. Field of the Invention
The present invention relates to a turbofan, and more particularly, to a blade part in a turbofan.
2. Background of the Related Art
Generally, a, blowing fan is used for forcibly driving air by a turning force of an impeller or a rotor, thereby making the blower applicable to a refrigerator, an air conditioner, a vacuum cleaner and the like.
Specifically, blowing fans include an axial fan, a Sirocco fan, a turbo fan, and the like in accordance with methods of driving air according to their respective shapes.
The turbo fan directs air from an axial direction of a fan and drives out the air through the gaps of the impeller, i.e., a lateral side of the fan radially. As air is naturally generated from inside the fan and flows out, the turbo fan requires no duct making it suitable for appliances of large capacity such as a ceiling type air conditioner or similar appliances.
FIG. 1 illustrates a layout of a general turbofan, and FIG. 2 illustrates a vertical cross-sectional view of the general turbofan in FIG. 1.
Referring to FIG. 1 and FIG. 2, a turbofan 1 according to a related art includes a shroud 4, a hub 2 coupled with a driving part 5, and a plurality of blades 3, each blade having one end coupled with the shroud 4, arranged at a circumferential part of the hub 2.
An inlet 7 to draw air inside is formed at an upper part of the turbofan 1. A plurality of flow paths 6 are formed at a central part of the turbofan 1 so as to direct the air drawn through the inlet 7. A plurality of outlets 8 are formed at a lateral side of the turbofan 1 so as to discharge the air.
The above-constructed turbofan according to the related art operates as follows. Once the turbofan 1 is rotated by a driving device, air is drawn in through the inlet 7 by the revolution of the blades. The air drawn through the inlet 7 flows out toward the outlets 8 along the flow paths 6.
FIG. 3 illustrates a cross-sectional view of the blade of the turbofan in FIG. 1.
Referring to FIG. 3, a cross-sectional shape of the blade 3 in the turbofan according to the related art forms an airfoil figure such as an NACA four digit airfoil or the like so as to provide an excellent aerodynamic characteristic. The airfoil configuration has great influence on the performance of the turbofan in power consumption, noise, and the like.
Specifically, time and cost of production depends greatly on the thickness of the blades of the turbofan according to the related art. If a cross-section of the blade is too thick, the cost of production increases. Also, the time required for manufacturing the turbofan by injection molding increases.
Accordingly, the present invention is directed to a blade part in a turbofan that substantially obviates one or more problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a blade part in a turbofan enabling to reduce thickness and cost of product of the turbofan.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following, or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a blade part in a turbofan includes a hub coupled with a rotating axis of a driving part, a plurality of blades arranged radially at a circumferential part of the hub, and a shroud coupled with a plurality of the blades and arranged so as to confront the hub wherein the blades lie between the hub and the shroud, and wherein each of the blades form an airfoil constructed with a top camber line defined by an NACA 4-digit airfoil and a bottom camber line lying closer to the top camber line than a bottom camber line defined by the NACA 4-digit airfoil.
In another aspect of the present invention, a blade part in a turbofan includes a hub coupled with a rotating axis of a driving part, a plurality of blades arranged radially at a circumferential part of the hub, and a shroud coupled with a plurality of the blades and arranged so as to confront the hub wherein the blades lie between the hub and the shroud, and wherein each cross-section of the blades is defined by NACA four digits, i.e., MPXX, so as to form an airfoil, wherein, if a chord line is an X-axis and a leading edge is an origin, and a chord c is 1, x is a chordwise, i.e., X-axis direction, relative coordinate and yt(x) is a thickness function so as to satisfy                     y        t            ⁡              (        x        )              =                  tc        0.2            ⁢              (                              0.2969            ⁢                          x                                -                      0.126            ⁢            x                    -                      0.3516            ⁢                          x              2                                +                      0.3100            ⁢                          x              3                                -                      0.1015            ⁢                          x              4                                      )              ,
wherein yc(x) is a Y-axis relative coordinate of a mean camber line and xcex8 is a slope of the mean camber line so as to satisfy                               0          ≤          x           less than           P                ,                  xe2x80x83                ⁢                                            y              c                        ⁡                          (              x              )                                =                                    M                              p                2                                      ⁢                          (                                                2                  ⁢                  Px                                -                                  x                  2                                            )                                      ,                  θ          =                                    tan                              -                1                                      ⁢                          {                                                                    2                    ⁢                    M                                                        p                    2                                                  ⁢                                  (                                      P                    -                    x                                    )                                            }                                      ,                                          P          ≤          x          ≤          1                ,                  xe2x80x83                ⁢                                            y              c                        ⁡                          (              x              )                                =                                    M                                                (                                      1                    -                    P                                    )                                2                                      ⁢                          (                              1                -                                  2                  ⁢                  P                                +                                  2                  ⁢                  Px                                -                                  x                  2                                            )                                      ,                                          θ          =                                    tan                              -                1                                      ⁢                          {                                                                    2                    ⁢                    M                                                                              (                                              1                        -                        P                                            )                                        2                                                  ⁢                                  (                                      P                    -                    x                                    )                                            }                                      ,            
and wherein a coordinate (xu,yu) of the top camber line of the blade is defined by xu=xxe2x88x92yt(x)sinxcex8, yu=yc(x)+yt(x) cos xcex8 and a coordinate (xl,yl) of the bottom camber line satisfies xl=x+yt(x)sinxcex8, yt(x)xe2x88x92yt(x) cos xcex8 less than yl(x) less than yu(x).
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.